Can YOU see something wrong here??

[pope 0]

What's wrong with THIS opening?
http://www.triaxproductions.com/trailers.htm

this is one of many similar [ahem] jumps at Bridge Day this year.

edit: changed link by request of original poster ~TA

[maretus 0]

Looks like he/she has way too small PC (or too short delay for that sized PC) resulting in a serious PC -hesitation and / or PC in tow. Secondly there is horrible snivel and oscillation of PC, both together resulting in an unpreferable opening sequence in base-enviroment and also some offheading. Thirdly he/she has modified skydiving gear with d-bag and packed slider up which in my books is not preferable configuration for any BASE-jump but at least not for 0-1 sec delays.

http://www.ufufreefly.com

[base428 1]

Or this guy (see attached pic). Check out his kneepad....

(c)2010 Vertical Visions. No unauthorized duplication permitted. <==For the media only

[BASE813 0]

just curious............... what are the rules for gear at BD?

[base428 1]

The rules for gear are pretty much the same as they've been for 17 years, and they probably won't change anytime soon (read the FAQ for more info).

Quote

just curious............... what are the rules for gear at BD?

(c)2010 Vertical Visions. No unauthorized duplication permitted. <==For the media only

[Rambo 0]

This looks very similar to the oscillating PC and scary opening that was on C2. Also there was a scene from a movie shown at bridge day on sat night that had two jumpers in wing suits shown flying with a large cliff to the jumpers left, the second jumper filming the first and a shot that showed a jumper dragging his toes off a cliff face. What movie was this from?

Party On!

[460 0]

Does it also look to you that the pilot chute has a bungee cord or something in its design to prevent its inflation until a critical speed, used to collapse the pilot chute while under canopy in the skydiving environment?

Looks like a death sandwich without the bread - Steve Deadman Morrell, BASE 174

[rendezvous 0]

Looks like the guy was using a collapsable pilot chute for it seems to hesitate to even inflate.

[base428 1]

I have several videos of "normal" PC's doing exactly what you saw in that video (hesitate for 1-2 secs). Just ask Tim C. from Spiders from Mars about his Tombstone 2 sec PC hesitation in the late 90's. *Any* PC can do this, as PC's work the majority of the time. Don't think that this couldn't happen to your brand new $100 PC.

(c)2010 Vertical Visions. No unauthorized duplication permitted. <==For the media only

[pBASEtobe 0]

What would cause that PC oscillation? It looked like it was pulling straight until the canopy started to come out the bag and then it just went all over the place. Could the initial opening shock of the PC contribute to that?

[jalisco 0]

Quote

What's wrong with THIS opening?

I'm no expert, but I wouldn't call this "oscillation". The pc looks grossly asymetrical, causing it to kite around, maybe due to design/construction flaws, or due to being connected incorrectly. It certainly has a lot of horizontal drive.

hmmm... what do you suppose would happen if you larks-headed your bridle around only one load tape?

[Treejumps 0]

THat is exactly what oscillation looks like. This a perfect example of poor gear setups that could kill or hurt you. The hesitation was likely caused by simply dropping the PC instead of throwing it. The oscilaation can be a number of things including 1. Poorly made PC. 2. Poorly maintained or overused PC 3. Incorrectly rigged gear- PC hooked up off center. Unless the PC/bridle larks head is grossly lopsided, that PC should be discarded. On a cliff that is all it takes to die.

Basically you had shit gear being jumped at the only place you can get away with it.

[KidWicked 0]

Quote

The hesitation was likely caused by simply dropping the PC instead of throwing it.

I disagree - he did about a .5 second delay (so very little burble), and his pitch doesn't look too bad.

Coreece: "You sound like some skinheads I know, but your prejudice is with Christians, not niggers..."

[tfelber 0]

All I have to say for both is LUCKY, LUCKY!!!

[SBCmac 0]

Just my opinion
Because we don’t know the gear configuration, I believe we are all shooting in the dark on this one… But I know it’s good to speculate on what could cause this. If I knew that the right PC was used for the given delay, that a BASE bridle was being used, that this was a BASE canopy, that this was a BASE rig being used, and that the proper delay was being taken for the use of a slider, I would be freaked the hell out by what I just watched. But from the looks of it, and I may be wrong, everything was wrong with this picture/jump… What I saw wrong with this jump... The wrong gear was being used with the wrong gear configuration for the given delay. In my opinion, this person had two options to prevent this… The first one being as simple as taking the proper delay for the given gear configuration (Smaller PC and Slider being used…). This would have decreased the time taken on the slider opening and the time the PC had to oscillate. Or, for this given delay, remove the slider and attach the appropriate PC. Again this would decrease the opening time for the canopy and the time the PC had to oscillate. The more time the fabric (PC and Canopy) sits out in the wind, the more time it has to cause problems, like PC oscillation and other canopy malfunctions (e.g. PC Hesitation, Line Twists, etc...).

Again, I wish we knew more about the actual gear used. But the #1 thing that sticks out in my mind is the fact that the wrong delay was taken for a slider jump…


SBCmac

[JohnnyUtah 0]

Quote

What's wrong with THIS opening?
http://www.triaxproductions.com/triax-BD04.mp4
(right click and "save as") or try:
http://www.triaxproductions.com/triax-BD04.avi

That pilot chute sure did have some wicked rotations in both directions. I agree with whats already been said that either the PC is attached uneven and/or the PC has a defect.

The hesitation doesnt look like it was caused by a bungee kill-line. You can see that the apex of the PC is not pulled down like it would be with a bungee.

Hard to tell if the mesh is small hole or large hole.

If you notice how the mesh is all squeezed together and just stays that way for nearly 2 seconds. This type of PC hesitation was one of the primary reasons I developed the Super Mushroom PC packing technique. I have seen several PC hesitations like this with good quality BASE pilot chutes while using the regular mushroom both going hand held and stowed. When packing using the regular mushroom technique, you stretch out the mesh, which also collapses it together, and then you s-fold it. The opening to the rip-stop is closed for the most part at the top end of the mesh column, and seems to stay closed until the s-folds unfold and the mesh starts to expand. From my observations through the years, I think on occasion it just takes a while for the air molecules to work their way into the collapsed mesh and subsequently into the canopy part of the PC. The Super Mushroom has the mesh already expanded for the most part. Also with the Super Mushroom, the mesh/rip-stop seam starts to expand on its own once it leaves your hand.

It also looks like the initial pilot chute rotation put 1 or 2 line twist into the lines below the slider before the slider started coming down which was probably a contributing factor to the long snivel. Since he had a d-bag, I wouldn’t be surprised if he had a sail slider as well.

Have Fun, Don't Die!
Johnny Utah
My Website
email:johnny@johnnyutah.com

[base570 1]

It looks as if the bridle gets hung up on something near the top of the container, which doesn't allow the bridle to get full extention thus putting the PC in the jumpers burble. It seems to clear from the top of the container then the PC gets to full extention and clean air then pulls everything else out of the container. One thought that comes to mind on the point of snag are the tuck flaps on the rig(if any). I can see an inexperienced jumper using the tuck flaps to 'stow' his excess bridle so it will have less of a chance to entangle with his arm. Maybe he used the tuck flap like the little piece of velcro some BASE rigs have to keep the bridle free. Maybe he had the bridle stowed elsewhere on the rig and it failed to release at the designated time. It seems to be trailing him from the middle of his shoulder blades

I also have to agree with the asymetrical PC too... what an oscillating bitch that is. Although it may have started to oscillate when it released from the snag point and had to find a new point to pull everything out from.

Jason
BASE 570

So does someone know what really happened or do we all have to guess and come to our own conclusions??

[JohnnyUtah 0]

Quite a few jumpers like to tuck a bit of bridle in the edge of a closing flap at the top of the rig when going hand-held. The primary reason for doing this is to keep the bridle from snagging around the bottom corner of the container. Perhaps a better way is to tuck a bit of bridle in the closing flap at the bottom of the container.

What I see on the video is that the PC inflates and then pulls the tucked bridle out.

Have Fun, Don't Die!
Johnny Utah
My Website
email:johnny@johnnyutah.com

[Treejumps 0]

Quote: "From my observations through the years, I think on occasion it just takes a while for the air molecules to work their way into the collapsed mesh and subsequently into the canopy part of the PC."

Hi Johnny,

Just to avoid any confusion about PCs, they do not inflate by capturing air inside the PC. Let me repeat this, as to be 100% clear: Pilot chutes do not capture air to inflate. A pilot chute generates lift exactly as a ram air canopy does, by having the air flow over the wing (around the round canopy). There are many reserve pilot chutes that use no mesh, but simply use F-111 where mesh normally is, and they inflate just fine. The mesh may improve some performance aspects, and it may take away others, but a PC is not a air capturing device.

Otherwise, I agree with what you posted. The PC delay appeared to be casued by simply releasing the PC instead of throwing it.

Cya.

[JohnnyUtah 0]

Hi Tree,

Two opinions are better than one. I posted simply to offer mine to maybe benefit someone else.

Is the reserve PC you are thinking of from a RW Vector? The vector PC does have a big hole in the bottom (same diameter as the spring coil). I do understand how a round parachute begins to open with a low pressure created on the outer surface of the canopy. For that low pressure to happen airspeed is required. On a BASE jump, I personally like my PC to open immediately even if there is zero to very little airspeed.

Once the round starts to open then air does rush into it inflating it quickly at that point. The round parachute is a drag device at that point and it works by capturing air.

I just dont agree with these two statements of yours.

Quote

Pilot chutes do not capture air to inflate.

a PC is not a air capturing device.

I hope there are no hard feelings if my opinion differs from yours.

Have Fun, Don't Die!
Johnny Utah
My Website
email:johnny@johnnyutah.com

[base311 0]

Quote

Quote: "From my observations through the years, I think on occasion it just takes a while for the air molecules to work their way into the collapsed mesh and subsequently into the canopy part of the PC."

Hi Johnny,

Just to avoid any confusion about PCs, they do not inflate by capturing air inside the PC. Let me repeat this, as to be 100% clear: Pilot chutes do not capture air to inflate. A pilot chute generates lift exactly as a ram air canopy does, by having the air flow over the wing (around the round canopy). There are many reserve pilot chutes that use no mesh, but simply use F-111 where mesh normally is, and they inflate just fine. The mesh may improve some performance aspects, and it may take away others, but a PC is not a air capturing device.

Otherwise, I agree with what you posted. The PC delay appeared to be casued by simply releasing the PC instead of throwing it.

Cya.

So you're saying a round parachute doesn't open by air forced into it from beneath? Rather, that the fabric is "sucked open" by airflow past the fabric on the outside? Where does the air that ends up inside the canopy come from and how does it open this way if it does not fill the inside from below?

Just trying to better my understanding of how rounds open.

Gardner

[460 0]

This is exactly what is being said Gardner. The Bernoulli principle dictates that most of the initial opening stages of pilot chutes and parachutes are from air flow on the outside, NOT THE INSIDE. This fact is well known among the parachute design community. Additionally, a detailed study of round openings will show that the canopy inflates from the top down, and at some point the bottom skirt has opened enough to finish the final stages of inflation. I believe this effect also predominates in squares, inflating from the top down resulting in a generally tail first inflation. Only problem is that the tail has the longest lines and line overs therefore can be a significant risk factor. Therefore, we use items like tailgates, etc to control the tail first opening sequence.

Johnny has a point though: knowledge of the very low speed environment is limited and anything that can be done to improve pilot chute performance can only help, obviously. Maybe we should consider adding taschengerts to pilot chutes too instead of just old ratty rounds.

I am also skeptical about any analysis of this video. It is just too difficult to see any real detail.

Looks like a death sandwich without the bread - Steve Deadman Morrell, BASE 174

[wwarped 0]

Quote

Quote

This is exactly what is being said Gardner. The Bernoulli principle dictates that most of the initial opening stages of pilot chutes and parachutes are from air flow on the outside, NOT THE INSIDE.

previously:

Quote

Just to avoid any confusion about PCs, they do not inflate by capturing air inside the PC. Let me repeat this, as to be 100% clear: Pilot chutes do not capture air to inflate. A pilot chute generates lift exactly as a ram air canopy does, by having the air flow over the wing (around the round canopy).

uh. no.
Bernoulli and his predecessors don't deserve such abuse.

Bernoulli's principle describes how total pressures balance and are a sum of static and dynamic pressures. fortunately for us, surfaces respond primarily to the static pressure. wings, or canopies, have relatively high pressure on the lower surface and relatively lower pressure across the upper surface. lift is generated. period. describing it as "air sucking the wing up" or "air pushing the wing up" are both valid.

the inflating pilot chute does not contain a vacuum. to inflate, air molecules MUST find there way inside and stay there.

thus the air inside the pilot chute is constrained and impeded (i.e. captured). it can not flow readily. with less airflow, the dynamic pressure is lessened, and the static pressure is higher. the converse is true on the exterior of the pc. increased airflow results in increased dynamic pressure, lessening the static pressure.

pilot chutes inflate simply because the static pressure inside the pc is greater than the static pressure outside the pc. it doesn't matter if you say "the air inside pushes the fabric out", or "the air outside sucks the fabric out." both are correct.

DON'T PANIC
The lies in learning how to throw yourself at the ground and miss.
sloppy habits -> sloppy jumps -> injury or worse

[460 0]

I am confused. My understanding is essentially that the principle is a simle expression relating pressure of a fluid to its velocity, and roughly explains certain aspects of wings, etc. Is there a reference you can point me to confirm your thoughts or mine? My background is not in air flow theory but in atomic theory.

Looks like a death sandwich without the bread - Steve Deadman Morrell, BASE 174

[TomAiello 26]

Ok, when a guy with a Ph.D. in physics starts looking for references, I think we're officially out of the depth of the average BASE jumper.

-- Tom Aiello

Tom@SnakeRiverBASE.com
SnakeRiverBASE.com